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Properties of Charges

Practice Questions:

Question 11: easy

Mark correct option :

1. The electric charge without mass is possible

2. The charge without mass is not possible

3. The electric charge may be transferred without transferring mass

4. Mass without electric charge is not possible

View Answer

The statement "The charge without mass is not possible" is correct based on our current understanding of physics because:

All known charged particles, such as electrons, protons, and ions, have mass associated with them. There is no experimental evidence of a physical entity that carries charge but has zero mass.
Even in the case of hypothetical particles like the photon, which is massless, it does not carry electric charge. Charged particles inherently possess mass due to their nature in both classical and quantum physics.

Thus, charge is always associated with some mass in all observed phenomena.

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Question 12: easy

In relativistic mechanics $m=\frac{m_{0}}{\sqrt{\left( 1-\frac{v^{2}}{c^{2}} \right)}} $ the equivalent relation in electricity for electric charge is:

1. q = q0

2. \[q=\frac{q_{0}}{\sqrt{\left( 1-\frac{v^{2}}{c^{2}} \right)}}\]

3. \[ q_{0}=\frac{q}{\sqrt{\left( 1-\frac{v^{2}}{c^{2}} \right)}}\]

4. \[ q=\frac{q_{0}v}{c}\]

View Answer

The relativistic formula for mass,

$m = \frac{m_0}{\sqrt{1 - \frac{v^2}{c^2}}}$

accounts for how mass increases with velocity. This behavior arises because mass is a form of energy, and energy is affected by motion under relativity.

However, electric charge (

$q$

) is invariant under relativistic mechanics. Charge does not depend on the velocity of the particle. It remains constant in all inertial reference frames, which is a fundamental principle in physics.

Thus, the equivalent relation for electric charge is simply:

$q = q_0$

This reflects the fact that charge does not vary with velocity, unlike mass.

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Question 13: moderate

Choose incorrect statement/s :

(A) In friction (method of charging), body having high work function will aquire positive charge.

(B) In conduction charge transfer takes place till potential of both bodies becomes equal.

(D) Induction is a body phenomena.

1. Only A

2. Only B

3. Both A and C

4. Both C and D

View Answer

Here’s the reasoning behind the incorrect statements A and C:

(A) Incorrect:

In frictional charging, the body with a lower work function (which requires less energy to remove electrons) will lose electrons and acquire a positive charge, while the one with a higher work function will gain electrons and acquire a negative charge. Thus, the statement is reversed.

(C) Incorrect:

In induction, the inducing body does not get an opposite charge. Instead, the induced charge on the other body is opposite in nature to the inducing charge, while the inducing body retains its original charge. Therefore, this statement is wrong.

Additional Notes:

(B) Correct: In conduction, charge transfer continues until both bodies achieve the same potential.
(D) Correct: Induction involves the rearrangement of charges within a body due to the presence of a nearby charged object. It is a property of the body itself.

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